Caption: Oil refinery. This is an atmospheric pipestill, a distillation tower (still) where hot crude oil is separated into parts called fractions. The crude oil, a mixture of hydrocarbons, is heated to about 400 degrees Celsius and piped into the bottom of this tower at atmospheric pressure. Hydrocarbon gases from the boiling oil rise up the tower towards the coolest area at the top. Different fractions are collected at different levels, depending on their boiling point. Fractions with a low boiling point (petroleum gases, petrol) rise towards the top of the tower. Fractions with a higher boiling point (jet fuel, diesel) condense lower down. The bottom fraction that doesn't boil is piped to a vacuum pipestill for further refining into parts such as fuel oil and bitumen. Photographed at ExxonMobil's Fawley Oil Refinery, Hampshire, UK.